@eggjs/errors

Errors for Egg.js

@eggjs/errors provide two kinds of errors that is Error and Exception.

• Exception is system error that egg will log an error and throw exception, but it will be catched by onerror plugin.
• Error is business error that egg will transform it to response.

Install

$ npm i @eggjs/errors --save

Usage

Create an Error

const { EggError, EggException } = require('@eggjs/errors');
let err = new EggError('egg error');
console.log(EggError.getType(err)); // ERROR

Create an Exception

err = new EggException('egg exception');
console.log(EggException.getType(err)); // EXCEPTION

You can import an error from an normal error object

err = new Error('normal error');
console.log(EggError.getType(err)); // BUILTIN
err = EggError.from(err);
console.log(EggError.getType(err)); // ERROR

Customize Error

Error can be extendable.

const { EggBaseError } = require('@eggjs/errors');

class CustomError extends EggBaseError {
  constructor(message) {
    super({ message, code: 'CUSTOM_CODE' });
  }
}

or using typescript you can customize ErrorOptions.

import { EggBaseError, ErrorOptions } from '@eggjs/errors';

class CustomErrorOptions extends ErrorOptions {
  public data: object;
}

class CustomError extends EggBaseError<CustomErrorOptions> {
  public data: object;
  protected options: CustomErrorOptions;

  constructor(options?: CustomErrorOptions) {
    super(options);
    this.data = this.options.data;
  }
}

Recommend use message instead of options in user land that it can be easily understood by developer, see http error.

HTTP Errors

HTTP Errors is BUILTIN errors that transform 400 ~ 500 status code to error objects. HttpError extends EggBaseError providing two properties which is status and headers;

const { ForbiddenError } = require('@eggjs/errors');

const err = new ForbiddenError('your request is forbidden');
console.log(err.status); // 403

Support short name too:

const { E403 } = require('@eggjs/errors');

const err = new E403('your request is forbidden');
console.log(err.status); // 403

FrameworkBaseError

FrameworkBaseError is for egg framework/plugin developer to throw framework error.it can format by FrameworkErrorFormater

FrameworkBaseError extends EggBaseError providing three properties which is module、serialNumber and errorContext

FrameworkBaseError could not be used directly, framework/plugin should extends like this

const { FrameworkBaseError } = require('@eggjs/errors');

class EggMysqlError extends FrameworkBaseError {
  // module should be implement
  get module() {
    return 'EGG_MYSQL';
  }
}

const err = new EggMysqlError('error message', '01', { traceId: 'xxx' });
console.log(err.module); // EGG_MYSQL
console.log(err.serialNumber); // 01
console.log(err.code); // EGG_MYSQL_01
console.log(err.errorContext); // { traceId: 'xxx' }

create frameworkError with formater

use the static method .create(message: string, serialNumber: string | number, errorContext?: any) to new a frameworkError and format it convenient

const { FrameworkBaseError } = require('@eggjs/errors');

class EggMysqlError extends FrameworkBaseError {
  // module should be implement
  get module() {
    return 'EGG_MYSQL';
  }
}

const err = EggMysqlError.create('error message', '01', { traceId: 'xxx' });
console.log(err.message);
// =>
framework.EggMysqlError: error message [ https://eggjs.org/faq/EGG_MYSQL/01 ]

FrameworkErrorFormater

FrameworkErrorFormater will append a faq guide url in error message.this would be helpful when developer encountered a framework error

the faq guide url format: ${faqPrefix}/${err.module}/${err.serialNumber}, faqPrefix is https://eggjs.org/faq by default. It can be extended or overridden by setting process.env.EGG_FRAMEWORK_ERR_FAQ_PREFIX (recommended) or, for backward compatibility, process.env.EGG_FRAMEWORK_ERR_FAQ_PERFIX (legacy typo).

const { FrameworkErrorFormater } = require('@eggjs/errors');

class CustomErrorFormatter extends FrameworkErrorFormater {
  static faqPrefix = 'http://www.custom.com/faq';
}

.format(err)

format error to message, it will not effect origin error

const { FrameworkBaseError, FrameworkErrorFormater } = require('@eggjs/errors');

class EggMysqlError extends FrameworkBaseError {
  // module should be implement
  get module() {
    return 'EGG_MYSQL';
  }
}

const message = FrameworkErrorFormater.format(new EggMysqlError('error message', '01'));
console.log(message);
// => message format like this
framework.EggMysqlError: error message [ https://eggjs.org/faq/EGG_MYSQL/01 ]
...stack
...
code: "EGG_MYSQL_01"
serialNumber: "01"
errorContext:
pid: 66568
hostname: xxx


// extends
class CustomErrorFormatter extends FrameworkErrorFormater {
  static faqPrefix = 'http://www.custom.com/faq';
}
const message = CustomErrorFormatter.format(new EggMysqlError('error message', '01'));
console.log(message);
// =>
framework.EggMysqlError: error message [ http://www.custom.com/faq/EGG_MYSQL/01 ]
...

.formatError(err)

append faq guide url to err.message

const { FrameworkBaseError, FrameworkErrorFormater } = require('@eggjs/errors');

class EggMysqlError extends FrameworkBaseError {
  // module should be implement
  get module() {
    return 'EGG_MYSQL';
  }
}

const err = FrameworkErrorFormater.formatError(new EggMysqlError('error message', '01'));
console.log(err.message); // error message [ https://eggjs.org/faq/EGG_MYSQL/01 ]

Available Errors

BaseError
|- EggBaseError
|  |- EggError
|  |- HttpError
|  |  |- NotFoundError, alias to E404
|  |  `- ...
|  |- FrameworkBaseError
|  `- CustomError
`- EggBaseException
   |- EggException
   `- CustomException

Questions & Suggestions

Please open an issue here.

License

MIT

Contributors

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